Following evidence submitted by Stop the Shaft, the Environment Agency is to be questioned by the Thames Tunnel Commission regarding the "flawed methodology" used to determine £400 million worth of work on the London Super Sewer. The Commission, chaired by Lord Selborne, has been established to independently examine the case for the 20 mile long sewer.

Sian Baxter, Chairman of Stop the Shaft, gave evidence to the Commission’s panel of experts revealing the Environment Agency’s methodology was not fit for purpose in determining which CSO (Combined Sewage Overflow) outlets should be connected to the Thames Tunnel. It costs tens of millions to connect each CSO and after analysing the Environment Agency’s methodology it became clear that a large proportion of this work will have a minimal impact on the cleanliness of the river Thames. It took 5 months of lobbying for Stop the Shaft to gain access to the methodology used.

After analysing the data Stop the Shaft can reveal that of the 34 CSOs originally designated for connection, 18 of these contribute to 98.7% of the pollution overflowing into the river. Tackling just these would bring immense improvements to water quality and yet the Environment Agency is asking Thames Water to connect a further 16 CSOs which account for just 1.3% of the total current CSO discharges into the river. This would be at a cost of over £400 million to be paid for by Thames Water customers who will reportedly pay an extra £10 a month “for life” to pay for the £3.6 billion Thames Tunnel.

Thames Water customers amount to one in four of all ratepayers in England.

Sian Baxter, Chairman of Stop the Shaft said:
“It is outrageous that ratepayers are being asked to pay for work that will have a minimal impact on the river especially given the current economic climate. It is scandalous that the Environment Agency is using such flawed methodology. We would like Caroline Spelman to account for this and explain why such expensive work has been recommended to take place without checking the true cost benefit.”

A spokesman for the Environment Agency told PutneySW15.com:

"The Thames Tunnel Commission was launched on 4 July 2011 in order to examine whether Thames Water’s plans for the Thames Tideway Tunnel form the best solution to stop sewage leaking into the River Thames.

The Commission has invited the Environment Agency, along with DEFRA, Thames Water, OfWat and the Consumer Council for Water, to offer written submissions and provide oral evidence relating to the plans for the Thames Tideway Tunnel.

He continued:
"The Environment Agency has sent its written submission to the Commission and has confirmed it is happy to attend an oral hearing. The Commission has not yet provided detail on any specific questions it may have for the Environment Agency relating to this matter."

One of the most shocking aspects of Stop the Shafts findings is that absolutely no independent review of the Environment Agency’s recommendations has taken place. The raw data is supplied by Thames Water and then subjected to a complicated and distortive selection process before the Environment Agency decides which CSOs must be connected.

The data supplied by Thames Water is questionable because they have only properly monitored the 9 pumped CSOs along the river. For the remaining CSOs they have relied largely on modelled estimations which are subject to error and cannot be said to provide an accurate representation of CSO discharges. If this was not flawed enough the methodology used by the Environment Agency to process this data has been found to be highly subjective and distorts the true picture.

“At a time when costs incurred by all other government agencies are subject to rigorous scrutiny, I cannot understand how the Environment Agency is allowed to be so profligate when it is ordinary householders, already under considerable financial pressures who will be asked to foot a bill for hundreds of millions” commented Sian Baxter.

Rather than simply measuring the actual amount of pollutant load at each prospective CSO the Environment Agency is happy to rely unquestioningly on modelled data. This data is then assessed on three criteria: pollutant load, health impact and aesthetics. In the absence of actual data the Environment are making assumptions, which STS know to be incorrect, for example, that discharges from all CSOs are equally concentrated. They are using highly subjective considerations in determining the aesthetics impact for instance, the number of complaints received from river users – this fails to take into account that sewage travels up to 10 miles in any one month so the source of the pollution complained about is unclear. Perhaps most shocking of all is the use of disproportionate factors/weightings that distort the relative impacts on individual CSOs. There can be no excuse for such deliberate distortion of reality.

As a result the Environment Agency is recommending that 16 CSOs be connected costing over £400 million even though they only contribute to 1.3% of the total current CSO discharges into the river. The recommendation is highly questionable particularly when there are projects, for instance further upgrade works to the highly polluting Mogden Sewage Treatment Works that may prove more cost effective in reducing pollution in the River Thames.

“We were shocked to discover quite how unprofessional the Environment Agency’s selection process is. Given the modelled data and questionable methodology, I can now understand why they were so loath to release the information to us” said Sian Baxter.

Stop the Shaft are calling on Caroline Spelman, Secretary of State for the Department of Environment, Food and Rural Affairs to investigate why the Environment Agency is asking ratepayers to stump up hundreds of millions of pounds to pay for work which would have a minimal impact on river cleanliness. At a time when all public works should be subject to the strictest scrutiny, it is outrageous that this has not already taken place.